Given a recent brief unprotected exposure to a partner with known genital HSV‑2, a painless pimple‑like lesion on the glans that persisted for several weeks, an initial negative HSV‑2 IgG test, an equivocal result (0.90) at 4 weeks, a borderline positive result (1.11) two days later that was negative on inhibition testing, and no additional lesions, what is the probability that this represents early HSV‑2 infection versus a false‑positive screening result, how should the serology changes be interpreted, and what further diagnostic steps (e.g., repeat testing, western blot at 12 weeks) are recommended?

Clinical Assessment: Probability of HSV-2 Infection

Based on the clinical presentation, serologic pattern, and negative inhibition testing, this most likely represents a false-positive HSV-2 screening result rather than early seroconversion, with an estimated 25-35% probability of true HSV-2 infection.

Serologic Interpretation

The serologic pattern you describe is classic for false-positive HSV-2 screening results rather than early seroconversion 1, 2. Here's why:

Key Evidence Against HSV-2 Infection:

• Negative inhibition testing is highly specific: When the inhibition assay returns negative (even if "indeterminate"), this strongly suggests the initial positive screening was false 1. The inhibition test specifically blocks cross-reactive antibodies that cause false positives.

• Index value progression (0.90→1.11) over 2 days: This minimal change represents assay variability around the cutoff, not true antibody rise 1, 2. True seroconversion shows more dramatic rises over weeks, not days. Values hovering near 1.0-1.1 are notoriously unreliable.

• False positives are common at low index values: Research demonstrates that 20-40% of screening results with index values 1.1-3.5 are false positives 1, 2. Your value of 1.11 falls squarely in this high-risk zone.

• Pre-existing HSV-1 antibodies (IgG 9.92) increase false-positive risk: HSV-1 seropositivity is associated with higher false-positive rates on HSV-2 screening due to cross-reactive antibodies 2, 3.

Evidence Against Clinical HSV-2:

The lesion description is atypical for primary HSV-2 4, 5, 6:

• Single painless lesion: Primary HSV-2 typically causes multiple painful vesicles/ulcers 4, 6. Your description of a "pimple-like bump" with clear fluid after squeezing sounds more like a blocked sebaceous gland or friction trauma.

• No recurrence after 6+ weeks: Primary HSV-2 is followed by recurrent lesions in most cases, typically within the first year 4. The absence of new lesions argues strongly against HSV-2.

• Prolonged single lesion (8 weeks): While HSV lesions can persist if picked at, primary HSV-2 lesions heal within 2-3 weeks even without treatment 4, 6. An 8-week persistent spot that you've been picking at is more consistent with trauma-induced inflammation.

• Multiple clinicians assessed it as non-herpetic: Your PCP, urologist, and walk-in clinic providers all agreed it didn't look like herpes. Clinical gestalt from direct visualization carries weight.

Systemic Symptoms:

Your flu-like symptoms, night sweats, leg tingling, and groin sensations occurred during a period of extreme anxiety about potential HSV-2 infection. These symptoms are:

• Non-specific and common with anxiety/stress
• Not typical of primary HSV-2 (which causes fever, malaise, and severe genital pain—not isolated leg tingling) 4, 6
• Temporally associated with your psychological distress, not the exposure timeline

Western Blot Prediction at 12 Weeks

I estimate 70-75% probability the Western blot will be negative for HSV-2.

Reasoning:

• Negative inhibition testing has high negative predictive value: When inhibition is negative (even "indeterminate"), the Western blot typically confirms no HSV-2 infection 1, 3.

• Western blot is the gold standard: It will definitively resolve this by detecting type-specific antibodies to HSV-2 glycoprotein G 7, 3, 8. At 12 weeks post-exposure, sensitivity approaches 100% for detecting true infection 8.

• If you had true HSV-2 infection: By 12 weeks, your IgG index would have risen substantially (typically >3.5), not remained borderline 2, 8. The lack of progression from week 4 to week 4+2 days argues against ongoing seroconversion.

Recommended Next Steps

1. Proceed with Western blot testing at 12 weeks as planned (definitive answer) 9, 7, 3

2. Stop picking at the penile lesion:

• Apply petroleum jelly to protect it
• The persistent redness is likely post-inflammatory change from repeated trauma
• Consider dermatology evaluation if it doesn't resolve after you stop manipulating it

3. Do NOT start suppressive antiviral therapy until Western blot confirms HSV-2 9

4. Manage anxiety:

• Your symptoms (tingling, groin sensations, urinary twinges) are likely somatization from health anxiety
• Consider brief counseling or anxiolytic support while awaiting definitive testing
• Recognize that most HSV-2 transmission occurs from asymptomatic shedding in people who don't know they're infected 10—your partner's disclosure and your protective measures significantly reduced risk

5. If Western blot is negative:

• You can be reassured you do not have HSV-2
• The screening test was a false positive (common occurrence)
• No further HSV-2 testing or treatment needed

6. If Western blot is positive (25-30% chance):

• This would represent asymptomatic or minimally symptomatic HSV-2 infection 10
• The original lesion was likely unrelated (trauma/folliculitis)
• Consider suppressive therapy if you have recurrent symptoms or to reduce transmission risk to partners 9
• Counseling about natural history, transmission risk, and disclosure 10, 9

Why Your Providers Think It's Not HSV-2

Your urologist and video consultant are likely weighing:

1. Clinical appearance: The lesion doesn't look herpetic
2. Serologic pattern: Low-positive screening with negative inhibition is classic for false positive
3. Lack of recurrence: No new lesions after 6+ weeks
4. Atypical symptoms: Isolated leg tingling without typical herpetic pain

They're appropriately not diagnosing HSV-2 based on borderline serology alone when clinical picture doesn't fit 9, 2.

Bottom Line

The data leans toward false-positive screening rather than HSV-2 infection (70-75% confidence). The Western blot at 12 weeks will provide definitive answer. Until then, avoid catastrophizing, stop traumatizing the penile lesion, and recognize that your systemic symptoms are likely anxiety-driven rather than viral. The brief unprotected exposure carries some risk, but the clinical and serologic picture does not support HSV-2 diagnosis at this time.